Conventionally, there are sheet transporting apparatuses that carry out a so-called unrestrained transport, in which the sheets are transported in a free state in which they are not restrained by transport rollers or the like. For example, guide members may be arranged on both sides of the transport plane of the sheets in such a device. The guide members on both sides form an air pool between the opposing faces respectively facing the transport plane. Air is blown from a direction that is orthogonal to the transport plane through air nozzles, which pass through the guide members, into this air pool. By blowing air, an air flow layer for transporting the sheets in a stable orientation between the guide members (between the two opposing faces) is formed.
With the above-described conventional transport apparatus, since the air is blown orthogonally from the sides of the transport plane of the sheets, the air flow in the air flow layer may become unstable in a situation in which no sheets are transported. For this reason, if a plurality of sheets are continuously transported, the air flow may become particularly unstable in the region between the sheets, which may cause a disruption of the transport orientation of the sheets.
In particular in apparatuses in which characteristics are detected by directing light at the sheets in such an unrestrained transport state, it may not be possible to stably pass the sheets through the focus position of the light if the transport orientation of the sheets is disrupted, thus lowering the detection precision due to blurring of the image.
Thus, there is a demand for development of a sheet transport apparatus that can carry out unrestrained transport of sheets in a stable orientation.